Injection timing adjustment mechanism for an injection pump of an internal combustion engine

An injection timing adjustment mechanism for an injection pump (7) of an internal combustion engine is proposed, in which the primary part (1) of the crankshaft of the internal combustion engine is driven, the secondary part (2) drives the camshaft (6) of the injection pump (7) and the torque is transmitted from the primary part (1) to the secondary part (2) by means of a helical toothing (4). An adjustment of the axial position of the secondary part (2) relative to the primary part (1) results, due to the helical toothing (4), in an adjustment of the rotation angle position of these two parts relative to one another, that is the injection timing is adjusted. A hydraulic tappet arrangement fixes the axial position of the secondary part (2) in relation to the primary part (1). At the same time a control piston (22) closes the outlets (32) to the two pressure chambers of the hydraulic tappets (12, 13). If the control piston (22) is displaced, it opens one outlet (32) from a pressure chamber (34, 35), whereupon the secondary part (2) can be axially displaced in this direction owing to the prevailing alternating moments. The position of the control piston (22) is controlled by way of a pressure of a second pressure medium. This pressure value of the second pressure medium is independently fixed as reference variable by a control device by way of an adjusting device as a function of a plurality of operating parameters of the internal combustion engine.